The proposed work is directed toward the goal of determining what role is played by carboxylesterases and carboxylamidases in the mechanisms of growth control and oncogenic transformation. This study includes both nonspecific enzymes and selected enzymes of recognized specificity including proteolytic enzymes and phospholipases. One goal is to determine if any of these enzymes are regulated by known hormones and mitogens both in the isolated form and in cultured cells. Possible regulatory roles of known products of enzymes of this type will be investigated by adding them to cultured cells, and by manipulating their concentrations in cultured cells using other means. A program to isolate variant cell lines that lack individual examples of these enzymes is in progress. BIBLIOGRAPHIC REFERENCES: a) Shier, W.T., and Trotter III, J.T. (1975). Lectin-enzyme conjugates: potential site-specific agents for enzyme therapy. Medicinal Chemistry Abstract #41, 170 Nat. Meeting, Amer. Chem. Soc. b) Shier, W.T., and Trotter III, J.T. (1976). Stimulation of Liver Microsomal Sialyltransferase Activity by Lysolecithin. FEBS Lett., in press.